Allegro Bipolar Stepper Motor Driver A3992

DMOS Dual Full-Bridge Microstepping PWM Motor Driver


Top Features

  • 1.5 A, 50 V continuous output rating
  • Low RDS(on) DMOS output drivers
  • Short-to-ground protection
  • Shorted load protection
  • Optimized microstepping via six bit linear DACs
  • Programmable mixed, fast, and slow current decay modes
  • 4 MHz internal oscillator for digital timing
  • Serial interface controls chip functions
  • Synchronous rectification for low power dissipation
  • Internal UVLO and thermal shutdown circuitry
  • Crossover-current protection
  • Inputs compatible with 5 or 3.3 V control signals
  • Sleep and Idle modes


Designed for pulse width modulated (PWM) current control of bipolar microstepped stepper motors, the A3992 is capable of continuous output currents to 1.5 A and operating voltages to 50 V. Internal fixed off-time PWM current control timing circuitry can be programmed via the serial interface to operate in slow, fast, or mixed decay modes.

The desired load current level is set via the serial port with two six bit linear DACs in conjunction with a reference voltage. The six bits of control allow maximum flexibility in torque control for a variety of step methods, from microstepping to full step drive. Load current is set in 1.56% increments of the maximum value.

Synchronous rectification circuitry allows the load current to flow through the low RDS(on) of the DMOS output driver during current decay. This feature eliminates the need for external clamp diodes in most applications, saving cost and external component count, while minimizing power dissipation.

Internal circuit protection includes short-to-ground, shorted load, thermal shutdown with hysteresis, and crossover current protection. Special power up sequencing is not required.

The A3992 is supplied in a thin profile (1.2 mm maximum height) 24 pin TSSOP (suffix LP) with exposed thermal pad and a 24 pin plastic DIP with dual copper batwing tabs (suffix B). The exposed thermal pad on the LP is at ground potential and needs no electrical isolation. Both packages are lead (Pb) free with 100% matte tin leadframe plating.

The A3992SB-T package variant is discontinued. Samples are no longer available. Date of status change: June 1, 2016. 

Recommended Substitutions: For existing customer transition, and for new customers or new applications, refer to the A3992SLPTR-T.


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